Why We Never Find Dinosaur Poo: New Explanation

Cockroach as maid? Yes, if you were a dinosaur.

Imagine you finish high school and you decide to go to University and study Palaeontology, insipired by Jurassic Park movies. So you start to understand the anatomy of Tyrannosaurs and Triceratops, and then, suddenly, one day you realize they must have pooped, like any other animal.

Since they were spread all over the world and they were giant, they should have produced a huge amount of excrements. Where have these gone? Why aren’t we encountering fossil poops (coprolites) everyday? How did they disappear?

That’s what Vršansky et al. (2013) investigated. A piece of amber containing dinosaurs’ coprolites located next to an ancient cockroach fossil was analysed by means of X- ray computed tomography, a powerful techniques that allows researchers to see what is inside an object without cutting it and that generates a three- dimensional image of the sample’s inner structure.

This composite fossil is from the Early Cretaceous, which stretches from 146 to 100 millions of years ago and is characterized by the presence of dinosaurs. The perfectly preserved roach belongs to the extinct family of Blattulidae and it is defecating. It is slightly embarrassing, yes, though fundamental to clearly state that one coprolite in the amber fossil is still extruding from the insect body. This means that the cockroach is the coprolite producer, and we cannot suppose an accidental vicinity.

Analyses on the coprolites revealed the presence of partially digested particles of wood. Based on the quantities, dimensions and the shape of the particles, the scientists were able to disclose that the wood must have been processed twice: once by endosymbionts in the hind guts of the cockroach, and, prior to that, by herbivorous vertebrates. Since dinosaurs were the main inhabitants of planet Earth, it is plausible to suppose that they were the herbivorous vertebrates that first ate the mentioned wood.

Further, the researchers compared the excrements from such amber fossils with other dinosaur coprolites and termites faeces to look for similarities and differences. The results showed that while there are major differences between termite’s and cockroaches’ dungs, the wood particles from dinosaurs’ coprolites do look like the wood particles from a cockroach, would they not have been digested by the insect.

In the end, dinosaur- age cockroaches were likely to be the main decomposers of dinosaurs dung. Thus, although cockroaches are among the most hated creatures nowadays, this time we should thank them for cleaning up and avoiding us to step into dinosaur poop every single day!

Here we see the dinosaur-age cockroach of the extinct family Blattulidae. (A– head to leg end length: 3.8 mm) with antennal sensory system (B, C) and five preserved coprolites (D– optical, E– surface rendering of numbered coprolites and dense particles based on the image stack from synchrotron X-ray microtomography; F– ST orthoslice with labelled boundaries and fragments). Lebanon amber 1094A-I. Scales 0,5 mm. (Vršansky et al., 2013)